Now, I'm not an absolute newbie; I know I can query several agents at once as long as the query/cover letters are personalized and I don't send copy&paste one to 9677 agents on the same day.
But I have this problem: while getting my MA I met a pro author who took a look at my writing, helped me fix some stuff and then introduced me to an agent. Face to face! I was far from finished with my novel, but Mr. Agent took a look and requested the full manuscript as soon as I had it.
Now I have it, written-rewritted-beta'ed, and have sent it to Mr. Agent as requested. But I don't want to count my laurels before they hatch: he requested the full, doesn't mean he'll take me on.
So question: would it be in good manners to query other agents even if Mr. Agent was nice enough to meet me in person and request the full even when I only had three chapters?