When a gain-to-hand Night is bought during the buy phase when the -1 card token is still on your deck, the card is topdecked.
Thanks for the bug report, SomeBunnyNewt1!
When I tried to replicate that problem with Guardian, Ghost Town, Night Watch and Den of Sin, however, the cards always ended up in my hand (and the -1 card token still 'there').
I checked your latest rated games (you can do this here: http://dominion.lauxnet.com/scavenger/ and I assumed you are SomeBunnyNewt) and there was only 1 where both a 'is gained to hand card' (Guardian) and a card that deals with the -1 card token (Relict) was present. But also in this case, everything seemed to be as it should.
Do you remeber which game it was (maybe against whom, maybe it is an older game not from the last 2 days)?
It was that game. There was a turn where I gained 2 Guardians and one of them ended up on my deck.
I just looked at the game again and I found what fooled you: (I/Ingix is you) You were not affected by the -1 card token but by Haunted Woods:
Turn 16 - Ingix
•I plays a Goons.
• L discards a card and a Copper.
• I plays 2 Coppers.
• I buys a Guardian.
I gets 1 VP from Goons.
I gains a Guardian.
• I buys a Guardian.
I gets 1 VP from Goons.
I topdecks a Guardian.
I gains a Guardian.
• I plays a Guardian.
I draws 2 Coppers, a Village, a Relic and a Guardian.
The first time you buy a Guardian you have no other card in hand, so Haunted Woods does nothing. The second time you buy one, the first one gets topdecked due to Haunted Woods (marked in log above), then the new one arrives in your hand. Of course, this happens so fast that it looks like the new Guardian is topdecked, because your visible hand never changed.
Thanks for the clarification!