I found a solution for this. Perhaps there are better solution.
I shift all values to be sure there is no more negative values.
Perhaps it should be useful to have such a method for this.
bbox = self.osm.get_bbox()
s_lon = lon + 10.0
s_lat = lat + 10.0
s_bbox_lat1 = bbox[0] + 10.0
s_bbox_lon1 = bbox[1] + 10.0
s_bbox_lat2 = bbox[2] + 10.0
s_bbox_lon2 = bbox[3] + 10.0
result = ( s_bbox_lat1 > s_lat > s_bbox_lat2 ) and
( s_bbox_lon1 < s_lon < s_bbox_lon2 )