As a rule, don't go for the high notes in the morning - you should take alot of time warming up, especially the low - as you go on, gradually go higher, but all in a mix - no belting - after your body and voice are going, then slowly add more air and get into the "full voice" sound.
The rasp could be any number of things - sinus draining, lack of rest, dehydration...to have literally strained a vocal chord, is a possibility, but highly unlikely from just warming up.
Remember that when you sleep, your body heals itself - and it rations that "healing energy" as to what is most vital for your survival - your voice is NOT vital to your survival, and therefore you need to be really well rested in order to be in top shape vocally.
Drink some "throat coat" tea with honey - no lemon - I'm sure you'll be fine.
"High time we made a stand and shook up the views of the common man" - Tears for Fears
