Pre-nap nap

Does anyone else's baby take a pre-nap nap? My baby will take a short 20-30 min nap and be fully awake for several minutes before going back to sleep. I think something disrupts her sleep when she's in the really light part of her sleep cycle. I've tried letting her put herself back to sleep, but she'll just play in her crib for 10-15 mins before crying. I don't mind going in and rocking her back to sleep, because she'll usually sleep for an hour or more when I put her back down. I just thought it was odd and wanted to see if anyone else's baby does it. I've tried just getting her up when she wakes up and it just turns into a very fussy couple of hours and she gets over tired. I've just been calling it her pre-nap. She does it at night too except it's for 45 minutes to an hour. She'll normally sleep 5-7 hours after putting her back down