Here's that question

You'd better have a chat with your mom...Whether or not she is flirting, being overly friendly, placating him or whatever, she needs to back off a bit...Your boyfriend is clearly drawn to her...Perhaps as a friend or parental figure, but also perhaps as a love interest...No matter what they feel for each other, you should not be in your room while your boyfriend and mother chat it up...Not cool...So talk with your mom...She needs to know that her friendliness or flirty ways needs to come to a halt before anyone gets hurt...And I would also suggest that you do not bring the boyfriend over to the house to just hang out...Plan some activities or hang out when your mom isn't around so much...After that, if you are still suspicious, drop the guy...You might be a young woman, but you sound like a very smart woman...You know when something is up...Trust your instincts...

The obvious question is, how hot is your mom?..Perhaps he's smitten, because she's a grown, mature woman, whereas you're just a kid (no offense)...Or, maybe he just gets along with adults really well...However, if your mom is nice looking and there's no dad in the picture, then it wouldn't shock me if he tried to make a play for her...
I have to say, though, and I'm not trying to sound like a parent, but you're too young to be with him...You're jail bait...I would hate to think this guy is using you to get to you mom, but you never know...Honestly, you should probably date men your own age, if you have to date...

It's definitely a sticky situation. Certainly, one option is to see how things play out, take it day by day, see if anything else happens that lead you to believe something else is going on with them. Another approach is to to talk to him about it, find out what he thinks of your observations, and what he wants to do...
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This second approach is a bit riskier, because of how awkward and difficult the conversation might be, but if you handle it right, plan out what you are going to say well, and try to stay calm, there's a chance no matter what he feels (for you, or your mom), things might stay... civil. I mean, he sounds a bit confused, like he doesn't know which female to get to know. There is a chance that it might not be you. Whether it's you or your mom he chooses, the best thing for you (to help your chances AND to make your feelings known) is to try to handle talks about this stuff calmly, and maturely, especially when you are angry or hurt...

Talk to your mom about it. I'm sure the last thing on her mind is stealing her daughter's boyfriend. It is possible that he fancies her but your mom can make herself more scarce when he's around or surely you can go to the movies or other things that don't involve your mom being around. It's quite likely your mom is checking him out to see if he is indeed mature enough to date her daughter and not a scoundrel that will break her heart. It's also quite likely that they just get on, he is older than you too, so he's probably used to socialising with older people. He is probably aware too that if he wants to keep dating you, he has to make a good impression with your mom....

It's not that weird that your mom talked to him when he called. It is a little weird that you were home and she didn't give the phone to you. If you weren't home, and your mom made some small talk, I think that'd be fine...
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I don't know if they're falling in love. I really doubt your mom would steal a guy from you. That just doesn't seem like anything any mother would do...