Transmission Fluid leaking from overflow bolt

[sheckay]

Hello. I just removed/added, removed/added, removed/added the transmission fluid on my IS250 2006. And I noticed a small amount of fluid leaking under my car. I put some cardboard under it to find out where it's coming from. And the drops are right below the overflow bolt. I lifted the car to verify. That's the only bolt that's wet. Now, it's in there tightly. Not overly tight. I'm confident that it's not a lose bolt issue. My question is, does fluid leak through it regardless of whether it's on tightly or if it's removed (as done when adding fluid)?
Thanks in advance.

[RX400h]

Is there a "crush" washer under the bolt head? If there is, it should've been replaced with a new one. Often, this type of washer is made of aluminum so that it conforms and seals adequately.

[sheckay]

re: 400h  Thank you for your reply. I'll have to jack it up and check. I happen to have a new crush washer for the drain bolt. I hope I can use that one.