hmmmm......you've got me puzzled on this one. Its not odd at all for her to want to nap every 2 hours, that's completely normal. What's not so normal is that her naps are so short. Most los at 4 months are getting 4-6 hrs of daytime sleep, and I'm guessing she's way short of that total. Daytime and nighttime sleep are organized by different areas of the brain, and los figure out night sleep first (0-3 mos) and day sleep later (3-6 mos), so it may just be a developmental phase.
I might try starting a wind down (after about 1 1/2 to 1 hr 45 min after waking), it doesn't need to be elaborate, just something to separate eating/activity and sleeping. With our dd, we do a diaper change, close the blinds, (when she was little we swaddled her), sit in the rocking chair, read a story, cuddle a bit, sing a song then into bed. When we were using pat/shh, we started pat/shh on our shoulder and then head to the crib. Its possible if you just help her ease into naptime with a wind down and starting a bit earlier that she'll actually nap longer.
All that said, enjoy the nights!!!