Having credit opened and closed in a short period of time is not a negative in your account. It is a nuetral.

The negative would come from having multiple inquiries on your account that cannot be grouped together. Grouped meaning that if your in the market for a car and go to several dealers they'll all qualify you for the loan based on your credit. These multiple inquiries would be reflected (or read) as one inquiry and will not damage your credit score. The time to have mulitple inquiries reflected as one used to be about one month but I think its been extended beyond that now, maybe someone who knows can enlighten us.