Steele shouldn't have mentioned it AT ALL. Claiming to have been discrete (while volunteering you sent the money) represented the end of being discrete.
There is no harm in doing so after the election. By then, it is too late for the Coakley campaign to launch the inevitable (Scott Brown: REPUBLICAN) attack ad.
After the election, you can't hide the money, anyway. So you might as well acknowledge it. You just don't do like the morons over at the DSCC, and issue a press release along with the money, because that puts the national party in the middle of a local race. The only reason to do it is because the Democrats are too insecure and self-promoting to let an apple-polishing opportunity go by. It is good to see that Steele has more sense than that.