Painting - Paint sliding off the wall

I painted a bedroom in my house last night and as I moved around the room, noticed that around the bottom as far down as the roller would go, the paint was sliding down the wall and gathering as a giant drip all the way around the baseboard. At first i thought I just didn't get it smoothed out, but after finishing and leaving the room for half hour or so, I noticed it's everywhere, above the doors, over the cold air return register. is this a paint problem or a roller problem? Today, I will have to sand that gunk off and touch up the areas.

I've painted over 20 rooms in the past five years, and painted 10 in this house in the past three months, and not seen this problem. I don't think it's "user error" but can't help wonder what it is. It's the same Behr paint we always use, the only difference between this and other cans is that it's "Ultra Pure White" instead of the "Accent Base" -- could that be it or did I just get a bad gallon?

I had this problem with some Behr paint myself recently. It was a 'flat' enamel but looked real shiny.

I fixed it by cutting in and rolling out 1 wall at a time, using the shortest nap for my roller, 3/8".

I would cut it in, roll it out, and roll sideways at top and bottom as close to the edge as I could with a very dry roller.

I don't know if we both got bad paint, or thats just the properties of this particular paint. IMO, Behr sux.

could that be it or did I just get a bad gallon

Many members report unfavorable results with Behr paints.