...do you just let them hang out in their crib, if they are happy?

LO is 13 months tomorrow and for the past few days I've been putting her down at the normal time (between 2 and 3pm) for her afternoon nap, but she won't sleep. She just hangs out in her crib. She just rolls around, stands up, cruises, hoots to herself, etc. She seems perfectly happy. I've let her stay in there for up to a half hour because she seems content and I get to have lunch. She doesn't cry at all or even fuss, she seems to enjoy it and she's usually more cheerful when I go get her. Am I a terrible mom?

ETA: I have a video monitor (Foscam) so I know exactly what she's doing