Ok so I have cracked speedometer glass.?

There's nothing OCD about wanting to get something fixed that you have to look at every time you drive your car, or that friends and associates will see if they ride with you.

Now, if you had a flowerpot on the patio that had a little chip out of one side that could be easily hidden, and you were agonizing over that, then the OCD label might be more appropriate.

As for the cracks, are you sure it's glass? Is this part of a fluorescent display? If not, it's probably plastic. Either way, cracking in glass or plastic can be the result of mechanical shock or stress. If someone didn't bump or punch the instrument panel, then there may be due to a manufacturing or assembly defect that's causing the glass/plastic part to be under stress once assembled.