I would be inclined to submit to the ATC in this case but only due to the fact that my chart would probably be way out of date (as a matter of principle).
However, I wouldn't be talking to any-one as is my right. It is also your right to fly right up to and along the boundary of the airspace. I'm guessing you were flying VFR so you were of course looking out of the window and identifying the ground features which run along the boundary. To be conservative you could fly up the radial with a half scale fly left indication.
Some controllers don't like people getting close to their airspace. Do not tolerate incompetance.
A friend of mine got a phone call from a controller once for doing aerobatics 'close' to his ATZ including threat of reporting. Said friend promptly took off and returned to area and called up on frequency and asked to have his position confirmed on radar. Turns out he was where he said he was and having established this was outside of controlled airspace he asked why, then, he would be reported for it. When asked to call when he landed he pointed out that he wanted the situation on tape and for the tapes to be pulled. Never had a problem again.
But you've got to be sure you're right to do this.