And I sincerely hope it will be the last.

I landed at LSE (LaCrosse) on the way home from the twin cities last
week. I landed on 18 and asked for a progressive taxi to the FBO,
having never been there before. Controller told me to turn left on
taxiway bravo down to the construction cones at the end.

As I was taxiing, I was about to cross 21, then recalled that the ATIS
had called 18 and 21 as active. I stopped, hard, but my nosegear was
over the hold line - in fact my mains were pretty much on the hold line.
I think it's important to note that the controller had not told me to
hold short of 21. If she had, then obviously this would have been a
pretty flagrant violation.

After a split second of uncertainty I told tower I was holding at 21.
She immediately told me to continue past in the chipper tone she had
been using all along. Note that nobody had landed on or departed 21
during the entire time of my taxi so there was no loss of separation.

I do believe that it was my responsibility to hold short of 21 even
though no explicit instruction had been given, though I'm not 100% sure
of that (but in the future I'll be damn sure to in similar
circumstances!). And, unless the controller deliberately wanted to make
me believe nothing was wrong for some reason, I believe she either
didn't notice I was over the hold (this intersection is pretty close to
the tower) or didn't care. Her voice indicated nothing out of the
ordinary, as I said. I know they don't 'have to' ask you to call the
tower or let you know they're making a report, though.

Though the logical side of my brain tells me that the chances of some
enforcement action here would be slim, of course I filed the form
regardless. I'd be interested in hearing people's opinions on that
matter (the chance of some investigation).