Sounds like a pretty good deal to me.
Generally if our first cut is going to be at heights like that we charge what you did, only if they're going to be a weekly customer.
Had a lady drive up to us last week. About a foot high, broadleafs that were 4 foot high here and there, wanted a one time mow for code enforcement. $125 instead of the typical $50ish. Double cut, just over an hour of work.