Very much so, that is what we mean by mixed emotions. On the foundational level he may have been enjoying God, but on a different level he is burdened. This is an important question. If we do not have a clear understanding of the goal, we will never get there. But we are not Vulcan.
Emotions are good.
There ought to be a part of us that is responsive and feels grief at the word of death or loss. This is the burden Paul felt for the saints. The foundational level is more like hope. Because we have hope in a better life, we can rejoice. We are to be joyful always in this foundational level but responsive to those around us in the upper level.