Yes, rollback reset any spam/offensive flags that were cast between the time of the revision being rolled back to and the time of rollback, as described in the faqthe faq:
Rolling back a post to a previous state will revert to the number of flags from that particular revision. This allows the OP (or someone else with edit rights) to rollback a post to which someone else introduced spam or offensive content in a later revision. However, as a general user, once you mark a post as spam or offensive, you cannot take it back.
Note your flag was not declined but rather disputed which has no negative effect whatsoever.