1999 Toyota 4Runner 2nd gear to 1st hard shift when cold

Hello,

I was hoping could give me some idea as to why my 99 4runners tranny has started acting up. It only occurs when its cold. The problem is when it does its first downshift from second to first. It makes a noticable thump and you can hear a metal to metal sound. Once its warm it shifts very smooth. Should I go ahead and take it to the dealer to get it checked out?

Thank you for any info...