White residue on rh cyclinder side

Just got an 08' WR250x with 3700 miles. I just noticed on the right hand side of the cylinder block that there is a hole in the center near the top. From this open hole there is a trail of white residue running down the side of the cylinder. It is dried out. What is it? Is it normal? I'll take a pic tomorrow if needed.

Weep hole for the spark plug. If the bike is washed & ridden in the rain & mud often enough some residue is probable okay.