Can ask what colors you decided on? Or if they're even set in stone yet? (my favorite blue is pms 300. Only marginally relevant, but I thought I'd mention it, hehe.)
Choosing pantone colors will certainly minimize discrepancy between various media, but it will by no means eliminate it, especially when going to print because of differences in printers. Even on the same printer, the same file can print a bit different from one time to another for a variety of factors. The great thing about pantone is that they have standardized color books that a printer can match against to be sure it's correct.
I believe Siera has all the numbers/hex's etc all written down somewhere (I think), and we'll publish them with the Style Guide once the logo's are complete.
It's not a perfect answer, but it is by far better then a random hex pulled from an old logo.