Bee Saga

On Sunday I spotted this bee on our one dalia. I quickly ran inside to get my camera, and I said, " I'll never get there before he is gone." Got the camera, took the photo, he stayed right in place, and I took several photos. His head was buried in the center of this flower, and he was totally oblivious to my presence 6 inches away. Went inside, got a different camera because I didn't think the photos were turning out very well, went back out and he was still there, apparently madly sipping nectar (I saw no sign of pollen but could see his proboscus). Took more photos. This continued for about an hour, and at one point another bee joined him, and he didn't even seem to notice. When we went to bed, he was still there. I looked a few times to see if he were actually still alive!
This morning he was in the same place, and I wondered if he remained waiting for the sun to warm him, or maybe he was protecting his territory. I don't know the habits of bees. I took this photo today.
After awhile it started to rain, and he moved down underneath one of the petals, where he stayed for a few hours. All at once he was gone.
Maybe he drank to much and couldn't lift off. Maybe he had a nectar hangover. I wonder.