CT2040 Bolt in Hydraulic filter

[OD512]

Preformed the 50 hour maintenance on my Bobcat CT2040H today. Everything went smoothly. However when I removed the hydraulic filter there was a bright shinny bolt and lock washer inside the filter. The bolt head is stamped DH 9. Any thoughts on where this could be from?

 

[winston1]

I really have no idea. Here is a picture of one of the bolts that holds the suction line on. I would speculate someone having a bad day when putting things together and maybe accidently or maybe on purpose put it in there. BOLT, 6697056

 

[OD512]

I have thought the same thing. Pic of bolt head.