It does sound like maybe he's in need of some more awake time. My ds was stuck on 45 minute naps as well at that age. He always seemed to rub his eyes and get tired at the same time...but when I put him down, he'd be up after 45 minutes. I just didn't get it...then I slowly increased his A time. Turned out, he was ready for some more. I actually think he rubbed his eyes out of habit! He is 7 mo. and still does it! To extend A time, if I remember correctly, I think it is best to do it slowly. For instance, for his morning A time, increase it by 15 minutes for 3 days in a row and see if there's any changes. What worked for my ds when we increased was to keep things very low key. We would lay on the bed and look at stuffed animals, walk around the house, look outside, look at books, etc.
When we were on a 3-3.5 hour routine, my ds also wasn't hungry then so we usually fed at the 4 hour mark and for quite awhile had A time before E.
Eventually the morning A time will get longer and it will definitely help stretch out the day so you won't have a long stretch in the evening.
I'm sure you'll get some great advice from others because I'm definitely no expert!