Yeah, that's never fun. I tried to play my brother's steel string guitar ounce, and then tried to play my violin latter that day, and decided that that had better go on my 'to-do list' for a little while.
i'm quite proud of my calluses. My finger tips are alittle numb, i've found if i take a break (like 1 day) it helps maintain them. They turned white once from playing so long. Sometimes, the impression of the strings will be there for a day or more.