Underground Fortress problem

[dlcatftwin]

Greetings! i enjoyed Underground Fortress - so much so that I'm doing it again. Now, I am in room 15698 -I am done with the (secret) rooms below and am ready to go back to continue with forward progress - but the door to the right (within the first column) is now closed! I don't remember that from before - what happened? What to do?
Thanks,
DLC

[rose]

Hi!
Are you sure you came through that column this time? Didn't you come from another direction? I can't remember it it s possible but if you can't get through now you haven't come the way you think. The door within the column is the kind that if it is opened it will stay open.

[Semi-Native]

Hmmm, that's never happened to me before. I just played it again, and it was fine.