Tacky or stickiness happens with overconditioning. This can easily happen applying too much product to the leather all at once the pores experience build up causing the leather to feel tacky or sticky.
To help avoid this, is best to apply a small amount of Blackrock and work from there. A little bit of our product goes a long ways.
However, there is no need for concern about the stickiness. It will fade away.
When this happens, get a cotton cloth to buff the leather to help dry it. If you have a horsehair brush, this will help to buff the leather. Then allow it to dry. Once it has been allowed to dry the stickiness will go away.
If it still feels tacky or sticky, use a straight leather cleaner to strip all the oils and give it a deep cleaning. Then apply a small amount of conditioner to replenish the oils in the leather.