probably right, but that got me curious so here goes:
From the link particularly the last paragraph.
http://www.fec.gov/pages/brochures/citizens.shtml"Designated Contributions
The Federal Election Commission (FEC) encourages you, when making a contribution to a candidate, to designate which election the contribution is for. By doing this, you will avoid any confusion as to which election limit applies to your contribution. To designate a contribution, write the name of the specific election on your check (or other written instrument). Or attach a signed statement with the same information.
If you do not designate a contribution to a candidate, your contribution automatically applies to your $2,400 limit for the candidate's next election. In other words, if you make3 an undesignated contribution after the candidate has won the primary but before the general election, your contribution counts against your $2,400 limit for the general. Similarly, if you make an undesignated contribution after the general election, it automatically applies toward the limit for the next election in which the candidate runs for Federal office.
If, however, you want a contribution to count against your limit for an election other than the candidate's upcoming election, you must designate the contribution. For example, suppose you want your contribution to count against the candidate's general election, even though the primary has not yet taken place. In this case, you must designate the contribution for the general. Or, if you want to help a candidate retire campaign debts for a past election, you must designate your contribution for that specific election.
Under certain circumstances, if you make an excessive contribution to a candidate committee, the committee may redesignate your contribution. When this occurs, the committee must notify you within 60 days, and must offer you the opportunity to receive a refund instead."