The percent of people coming in with trade-ins is down from its peak level, says Edmunds.com senior analyst Jessica Caldwell, but this might actually be a good sign.

In a conference call to discuss May auto sales, Caldwell said this trend likely points to “people adding to their fleets rather than just replacing.”

The average age on trade-ins, Caldwell also said during the call, is over six years.

Tuesday’s call also covered some of the impact from the General Motors recalls. Based on the latest monthly sales results, the attention doesn’t seem to be hurting GM.

The automaker reported Tuesday that the 284,694 cars it sold in the U.S. last month marked  its strongest May since 2007 and its best month (May or otherwise) since August 2008.

“The momentum we generated in April carried into May, with all four brands performing well in a growing economy and 17 vehicle lines posting double-digit retail sales increases or better,” said Kurt McNeil, U.S. vice president of sales operations.

In a bit of analysis sent out prior to the call, Caldwell said: “Despite the overwhelming amount of attention placed on the GM recalls in May, car shoppers don't seem to be holding anything against GM brands. 

“Shopper consideration for every GM brand has remained consistent through the recall headlines. Many people may not realize that GM is the parent company of these brands, but others may be overlooking the trouble with older models and simply seeking shiny new sheet metal that serves their needs,” she added.