I think I get this a bit most of the time, but it has become particularly noticeable with the British cold, damp, gloom to which I've been subjected this last week.
When I start my practice session, for a good half hour (even more today), my lips feel too stiff to vibrate properly unless I give the note loads of oomph. It's sort of great for the high notes because they're all there, but low on the stave I'm just airballing like crazy.
I live on ciggies and strong, black tea so let's get over that one.
Anybody have any hints on increasing lip suppleness in a reasonable timeframe, preferably without doing extended Champion the Wonderhorse impressions in public?