gf burst into tears during sex

to put things into perspective she is a self proclaimed non-cryer who almost never cries/gets super emotionally expressive. we’ve been together about 7 months and the only time i saw her cry was when i got her a sentimental gift. in the bedroom, if she’s not 100% about something she’ll tell me. i checked in constantly if what i’m doing is okay and she said yes everytime. so basically i pulled away from her (for added context we were using a strap she was bottom in doggy style position) and she sat up and just bursted into tears. i was terrified i hurt her but she insisted she was fine and we cuddled until she calmed down. she chalked it down to a “weird moment” and insisted i didn’t do anything wrong. i’ve cried during sex before but even then it’s more of an “overwhelming pleasure cry”. hers was like a genuine breakdown as if she was upset - this was incredibly out of character for her usually nonchalant self and honestly it has concerned me quite a bit. we’ve just moved past it like nothing happened but i’m still concerned about what that was and whether she’s not telling me something.